 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] SMS: B08062      ]
 ] D.L. ENTWISTLE     ]    BFS PROGRAM NOTE         ]                  ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:            ]
 ]  382-510  2-2634   ]      RELEASE NOTE ( )       ] 06/01/81         ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]       11.04 AND SUBS          ]  CREW ( )  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]           MAJOR SOFTWARE AREA:            ] OPS MODES AFFECTED:     ]
 ]BSL( ) BSS(X) GNC( ) SEQ( ) SM/SP( ) IPL( )] 0, 1, 3, 6              ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: DOWNLIST                                         ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: MG038101/3.7.1.2                               ]
 ]_____________________________________________________________________]
 ] TITLE:  LOSS OF DOWNLIST FRAMES                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ]  DUE TO TIMING DIFFERENCES BETWEEN THE BFS GPC AND THE              ]
 ]  PCMMU, THE PCMMU MAY PERIODICALLY REJECT A SINGLE BFS              ]
 ]  DOWNLIST FRAME.  THIS WILL HAPPEN IF IN THE LONG TERM              ]
 ]  THE PCMMU READS THE TOGGLE BUFFERS AT A SLOWER RATE THAN           ]
 ]  THEY ARE BEING FILLED BY THE BFS.                                  ]
 ]  WHEN TRACKING THE PFS, BFS DOWNLIST OUTPUT TIMING IS               ]
 ]  DEPENDENT ON TRACKING OF THE PFS I/O PROFILE.  WHEN NOT            ]
 ]  TRACKING PFS, BFS TIMING IS DEPENDENT ON INTERNAL GPC              ]
 ]  HARDWARE AND SOFTWARE.  WHETHER OR NOT FRAMES ARE                  ]
 ]  REJECTED - AND THE TIME BETWEEN REJECTED FRAMES -                  ]
 ]  DEPENDS ON THE CURRENT ENVIRONMENT AND THE TIMING                  ]
 ]  CHARACTERISTICS OF THE PARTICULAR GPC AND PCMMU IN USE.            ]
 ]  THIS DOES NOT APPLY TO HISAM DUMPS, WHICH USE SPECIAL              ]
 ]  TIMING TO PRECLUDE LOSS OF DATA.                                   ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]                                                                     ]
 ]  BE AWARE THAT OCCASIONALLY (APPROXIMATELY EVERY 16                 ]
 ]  MINUTES) ONE DOWNLIST FRAME MAY BE LOST.                           ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                   CP      ]APPROVAL:                    ]
 ]RI:<S>D.L. ENTWISTLE      DATE 07/29/88]                             ]
 ] --------------------         ---------]                             ]
 ]SSD: SAM ANKNEY           DATE 08/10/88]                             ]
 ] --------------------         ---------] JACK BOYKIN        08/17/88 ]
 ]PF MGR: MICHAEL BRIEDEN   DATE 08/09/88]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_____________________________________________________________________]
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